1. Field of the Invention
The present invention concerns a multi-cylinder engine and a method for alternatively producing multi-cylinder engines.
2. Earlier Technology
There is a conventional example of the multi-cylinder engine as shown in FIG. 16 (for example, see Patent Document 1).
Like the present invention, on the assumption that a longitudinal direction of a cylinder block 101 is taken as a front and rear direction, this conventional technique provides in the cylinder block 101, a consecutive side water passage 103 oriented in the front and rear direction and passing by each of cylinder walls 112 and introduces cooling water from a radiator to a cylinder jacket 104 laterally via the side water passage 103.
However, this conventional technique is different from the present invention on the following points.
The conventional technique provides only at a font end portion of the side water passage 103, an opening 103a which communicates the side water passage 103 with a water pump 110, but it does not arrange such an opening at a rear end thereof.
The side water passage 103 has an outer wall opened in the front and rear direction to provide a plurality of holes. Although the Patent Document 1 does not explain for what purpose the holes are provided, it is considered that those holes are in an attempt to remove the core sand intended for forming the side water passage after having cast the cylinder block 101.
Patent Document 1
Patent Public Disclosure No. 60-190646 (See FIGS. 1 and 2)
The conventional technique has the following problems.    <Problem> It costs high to produce the engine.
When producing an engine of a different specification by replacing the cylinder block, the following matter is considered.
For example, while an engine which has a water pump arranged at a front end portion of the cylinder block is deemed as an engine of front-end pump arrangement type, an engine which has a water pump arranged at a rear end portion of the cylinder block is regarded as an engine of rear-end pump arrangement type. In this case, it is considered to replace the cylinder block of the engine of the former specification with the cylinder block of the engine of the latter specification and vice versa.
However, as shown in FIG. 16, the cylinder block of the conventional engine is only at the front end portion of the side water passage 103, provided with the opening 103a which communicates the side water passage 103 with the water pump 110 but is not provided at the rear end portion thereof with such an opening. Therefore, it cannot be replaced with the cylinder block of the engine of rear-end pump arrangement type.
As such, in the conventional multi-cylinder engine, it is impossible to replace the cylinder block with another one, which entails a high production cost of the engine.